Bluetooth compatibility in Octavia Mk2 ('05)

Hi! I recently bought an Octavia Elegance Mk2, 2005 - annoyingly unlike an '07 Mk2 that I already had experience with, it does not have an aux port under the armrest.

I now have a phone with no aux-port as well - I would usually buy an aux-to-bluetooth adapter for my car, but the car doesn't allow this. I wonder what modification I can easily make to connect my phone to the car speakers? Do I need to open up the radio and wire an aux port in, then stick an adapter on for bluetooth? Is there a really simple and elegant solution out there?

Thanks all!